1. Field of the Invention
The invention relates to acoustic echo cancellation (AEC), and more particularly, to systems and methods for acoustic echo cancellation.
2. Description of the Related Art
Acoustic echo arises when sound from a loudspeaker (e.g. the earpiece of a handset) is picked up by a microphone (e.g. the mic in the same handset). The problem exists in any communications scenario where there is a speaker and a microphone close thereto. Direct sound from the loudspeaker (not the person at the far end, otherwise referred to as the talker) enters the microphone mostly unaltered, which is referred to as direct acoustic path or linear echo. The difficulties in canceling acoustic echo stem from the alteration of the original sound by the ambient space. The alteration colors the sound that re-enters the microphone. The changes can include certain frequencies which are absorbed by soft furnishings, and reflection of different frequencies at varying strength. The secondary reflections are not strictly referred to as echo, but rather reverberation. Acoustic echo is heard by the far end talker in a conversation. So if a person in Room A talks, they will hear their voice bounce around in Room B, which is referred to as nonlinear echo. If the echo is not cancelled, it will be transmitted back to its origin. Due to slight round-trip transmission delay, the acoustic echo is very distracting.